/Engine/Source/Runtime/Engine/Classes/Engine/SkeletalMesh.h
Return true if the imported data has all the necessary data to use the skeletalmesh builder. Return False otherwise. Old asset before the refactor will not be able to be build until it get fully re-import. This value is cache in the LODModel and update when we call SaveLODImportedData.
bool IsLODImportedDataBuildAvailable ( const int32 LODIndex ) const